Tag: Oak

Sometimes it seems like there’s no end to the range of projects we can make with a CNC machine. And it’s quite amazing that even cheap versions are accurate enough to make miniature projects for model scenery and even dolls houses. So I thought it might be fun to try making some miniature fruit crates, as the photo above shows, and post the design here for anyone to have a go at making some too. At full size they would be around 450mm long, 300mm wide and about 200mm high but at 1/12th scale, commonly used for dolls houses, they’re much smaller: I’ve included a photo below with a one pound coin for comparison.

I’ve put an SVG file below for you to download, or you can click here to launch it in the GCoderCNC web-app. If you need to edit it, or make a DXF file for your CNC software, you can do that with Inkscape quite easily. The red box is there in case you need to get scale in your software, but doesn’t need to be cut: it should be 70mm wide by 65mm high for 1.5mm thick wood (or other materials such as plastic, or even cardboard, if you prefer). If you use thicker material you can scale it proportionately, such as 2x scale for 3mm thickness. The design works for LASER cutting but can be adjusted easily for routing by offsetting the lines through half the cutting width.I LASER-cut a prototype in Oak (the one on top in the photo above) and the rest in Basswood, both from 1.5mm sheets. Once cut they are quite simple to put together. I started by putting the sides onto the bottom of the crate, then slipped the ends on one at a time. I also used glue at all the push-in joints: the base could be left floating but the glue helps prevent the thin pieces of wood at the joints breaking away when sanding. To finish the crates off I used 400 and 1000 grit sandpaper, including using a finger sander, followed by a couple of coats of Danish Oil to give the wood a nice look without too much of a shine. Personally I’m quite happy with the results and hopefully you’ll enjoy making some on your CNC machine too 🙂

After all the love and care we put into our CNC projects their success often hinges on how well we finish the exposed wood surfaces. Sometimes we may just want to leave them plain, even unsanded, but usually we’ll be wanting to bring out the colour and grain structure to show off the beauty of the wood we’ve chosen. So what is the best way to do that? Should we just cheat and use clear-coat, or should we use traditional techniques like Danish Oil or Shellac sanding sealer? How much work is involved varies a lot depending on which we choose, so is the best way the one that involves the most perspiration, or can simple ways provide more inspiration?

To try to answer some of those questions I decided to do some tests with six of my favourite woods: Basswood, Oak, Cherry, Walnut, Mahogany and Birch plywood, as shown in the photo below. I then decided on four finishes: plain unsanded wood (A), Plasti-Kote aerosol clear-coat (B), Danish Oil (C) and Shellac sanding sealer (D). The last three were all done in two coats and after light sanding with 400 and 1000 grit sanding paper/pads. I think one of the most interesting things the photo shows is that all three surface finishes, even the simple spray-on clear-coat, enhanced colour and grain significantly.

The unsanded woods (A) were obviously a little plain and dull, but still nice for many uses. The simple clear-coat (B), however, was much more interesting as it’s a very simple finishing process yet brought out the colour and grain structure very well. The main comment in comparison to the other finishes is that it gave a slightly darker look to the wood, although not in an unpleasant way. In comparison, I think the Danish Oil (C) gave a slightly nicer look to the grain, as well as bringing out the colour of the wood beautifully. Probably that’s due to it being mostly oil (see my post here) and so likely soaked deeper into the wood surface before hardening.

The sanding sealer (D) also gave a nice finish, although it was slightly duller. That’s not surprising though as its’ purpose is mostly to provide a sealed surface that can be lightly sanded smooth before applying other coatings. In the past I’ve used it with a finish of wax polish for a traditional look, and I think that would work well with the results here. The only other thing to note is, for me anyway, that the finishes improved the plain colours and grains of the Basswood and Birch plywood, even giving them some of the look of pine which could be useful for many projects. However, for a more exciting look they may benefit from a little wood stain/dye: in the case of the Danish Oil that can include darker oils that are commonly available.

Overall, I think the main conclusion from my tests is that simply applying a synthetic clear-coat to a carefully sanded wood surface is just as effective as more traditional techniques. Certainly it enhanced the colour and grain of all of the woods as well as giving an extra level of darkness if that’s what you want. Of course, using the other, more traditional, techniques gives subtly different effects so they still have a role to play and can be used with a final clear-coat too for some nice effects. Really it’s all down to our judgement, but without any need to feel guilty that using a cheap and simple clear-coat is cheating: in fact it’s a useful technique that compliments traditional finishes very nicely.

Oak is a widely used wood that crops up time and again in things like furniture and traditional building techniques. It has a distinctive look and feel, making it something that we’re likely to want to use in a CNC machine sometime. So I decided to try cutting a 1.5mm sheet of it with my 5W diode-LASER mounted on my CNC. The results are in the photo above and you’ll notice that it was relatively easy to cut (much easier than, say, Mahogany), with one pass at 75% LASER-power and a feed rate of 100 mm/min being useful settings for future cutting work. As you can see in the photo below, using a higher power, or multiple passes, can result in more charring around the edges. The Oak had a water content around 11%, after being kept indoors for a few weeks, so wasn’t overly dry or damp.